1. Field of the Invention
The present invention relates to control knob dial illumination in general and in particular to the use of an electroluminescent panel surrounding, a part of, or adjacent to, a control knob such that when the control knob is to be positioned in insufficient light or in darkness, the electroluminescent panel may be illuminated to illuminate the dial so that proper settings can be made.
2. Description of Related Art
During the filming of a movie or other type of film or video production, the responsibility of the camera assistants or operators is to focus the camera. This is done by turning a control knob on the side of the camera. By turning this control knob, the assistant or operator may change the focal length of the camera lens or cause the camera to perform other functions. For instance, if an individual being filmed were to walk from a position ten feet from the camera to a position three feet from the camera, the camera assistant or operator must turn the control knob to change the focal length so that the individual will stay in focus. In the situation just described, the camera assistant or operator would mark on a plastic disk, associated with the knob that he must turn, some type of reference mark indicating, for example, three feet, five feet, seven feet, nine feet, and the like. By this means he would know how far to turn the control knob for a particular distance. When these marks on the disk line up with a stationary witness or reference mark on the body of the camera or the body of the remote control unit, the camera is focused at the indicated distance. These marks are always changing when particular shots, lenses, angles, or subjects change. Thus there is a constant need to correct the data on the disk associated with the control knob. In many cases, remote servo lens controls are used for the same purpose as the controls that are actually on the camera. Such controls are used when the assistant or operator is unable to move with or work next to the camera. Sometimes because the camera is moving freely or because it is mounted in a way that the assistant or operator could not get to it, such as when the camera is mounted on some type of crane, a remote servo controller would be used. Most of these remote servo controllers have a disk or similar surface on which selected indicia is placed by the assistant or operator. Thus by turning the control knobs on the remote servo control boxes, the assistant or operator can focus, zoom in or out, and change iris settings on the camera lens from a distance. Again, each of these control knobs have a removable and replaceable annular disk associated with the control knob on which indicia can be placed by the operator or camera assistant to indicate where the control knob must be positioned for a given situation.
The current problem of not being able to see these controls and their associated indicia carrying disks in low or no light is solved by the assistant or operator shining a small flashlight on the disk. Otherwise he may use a rather clumsy accessory light on the camera itself. However, none of these methods illuminate the disk associated with the control knob or utilize a backlighting feature.
Panels for use in backlighting are well known in the art and include such panels as electroluminescent panels. These devices glow with different colors depending upon the material from which they are constructed and have been used for many purposes. In U.S. Pat. No. 3,738,239, an electroluminescent element is placed under an exposure calculating dial of an electronic flash or camera to illuminate the scale portions of a camera to permit reading of the camera scales in little or no light. In Patent '239, the electroluminescent material is placed under the rotating dial and the entire dial is illuminated as it is rotated. However, such backlighting of disks surrounding a control knob or associated with a control knob either on an object such as a camera or on an object such as a remote servo control unit, creates special problems that need to be addressed such as the connection of control circuits to the electroluminescent panel. Further, it would be desirable to retrofit existing units that have plastic disks associated with the control knob.